I propose to study the neural basis of visual pattern recognition in fish by anatomically localizing the visual pathways involved, as well as by recording the electrophysiological response of neurons in the optic nerve and optic tectum to visual patterns which are known to be behaviorally relevant. By studying a relatively simple vartebrate system using biologically significant visual stimuli, I want to analyze the processes used in detecting visual patterns. The African cichlid fish, Haplochromis burtoni, has been chosen for study because it has a restricted set of color patterns which are used for species-specific visual communication. In previous work, I have found that this fish uses a particular region of the retina for detailed viewing, although there is no specialization evident in its retinal anatomy. A standard behavioral paradigm will be used in selectively encircling or ablating that portion of the retina by laser coagulation. Following the lesion, degenerating axons will be followed histologically using silver impregnation methods. The neurophysiological recordings will be made in the optic nerve fibers from neurons in the optic tectum. The neural response to a standard array of bars and spots, as well as to a selection of visual stimuli used by the fish in species-specific social communication, will be studied. In addition, the retinal projection onto the optic tectum will be mapped electrophysiologically.